The people are understandably Brexit weary. But after two-and-a-half years of phoney war, this issue has finally reached its decisive phase.

Tomorrow, UK Prime Minister Theresa May has a date with fate and there is little doubt that she will fail to get her EU-UK divorce through the Westminster parliament. What happens thereafter is a matter of conjecture with a variety of scenarios to be sampled from.

It will make for a very uncertain week in London, and Brussels, where EU leaders gather for a summit on Thursday. In any semblance of "ordinary politics", Mrs May would be history by then, leaving the job of prime minister swiftly and with as much dignity as she could muster.

Presenting a way forward on her country's biggest constitutional change in 40-plus years, and failing to get it ratified, more usually could end only one way.

But the UK's politics is seriously up in a heap right now, meaning these are far from ordinary political times.

So, even if the Labour Party moves its threatened motion of no-confidence in the prime minister, there is no guarantee it will succeed. The Conservative Party colleagues, who cannot support their leader's draft Brexit deal, and the 10 Democratic Unionist Party MPs declared vehemently against it, appear more likely to keep Mrs May in office, though very far from being in power.

We must acknowledge that the Irish Government has managed well in a very difficult situation over these turgid and tough negotiations, which have ensued since British voters opted on June 23, 2016, to end over 40 years of EU membership. In the Brexit gut struggle Ireland has won many battles - but the war still remains undecided.

It is a matter of considerable regret to everyone on this island that the British side played a bad hand over 18 months of Brexit talks. Ill-judged opening stances led to a number of damaging climbdowns that have added to Mrs May's difficulties in selling a draft Brexit deal that now carries her name.

The biggest climbdown came over Ireland. One year ago, Mrs May signed a formal agreement with the EU guaranteeing no physical border in Ireland after Brexit. Despite doubts, that guarantee still stands and the odds of it persisting still rest favourably with Dublin.

But, as we head into uncharted political waters, none of that can be taken for granted. Changes, or embellishments, facilitating a UK fallback will probably involve modifications, or elaborations, on the backstop. Ireland must be eternally vigilant.

At the same time the spectre of a "no-deal Brexit" continues to loom. We need reassurance that necessary preparations are being made at this uncertain time to face that.